From fd32bcf547f57cf1a10a6e6438fb7d6c871f8ac3 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Sat, 25 Apr 2026 00:24:05 +0000
Subject: [PATCH] lua: string.format width/zero-pad/hex/octal/char/precision +6
 tests

---
 lib/lua/runtime.sx      | 133 +++++++++++++++++++++++++++++++++++-----
 lib/lua/scoreboard.json |  58 ++++++++----------
 lib/lua/scoreboard.md   |  35 +++++------
 lib/lua/test.sh         |  22 +++++++
 plans/lua-on-sx.md      |   1 +
 5 files changed, 183 insertions(+), 66 deletions(-)

diff --git a/lib/lua/runtime.sx b/lib/lua/runtime.sx
index 118f9071..3c148e08 100644
--- a/lib/lua/runtime.sx
+++ b/lib/lua/runtime.sx
@@ -1145,6 +1145,39 @@
       ((= (type-of n) "number") (str (floor n)))
       (else (str n)))))
 
+(define
+  lua-fmt-pad
+  (fn (s width left-align zero-pad)
+    (let ((diff (- width (len s))))
+      (cond
+        ((<= diff 0) s)
+        (else
+          (let ((pad (lua-string-rep (if (and zero-pad (not left-align)) "0" " ") diff)))
+            (if left-align (str s pad) (str pad s))))))))
+
+(define
+  lua-fmt-int-base
+  (fn (n base upper)
+    (cond
+      ((= n 0) "0")
+      (else
+        (let ((sign "") (v n) (out ""))
+          (begin
+            (when (< v 0) (begin (set! sign "-") (set! v (- 0 v))))
+            (set! v (floor v))
+            (define
+              ib-loop
+              (fn ()
+                (when (> v 0)
+                  (let ((d (- v (* base (floor (/ v base))))))
+                    (let ((c (cond
+                               ((< d 10) (char-at "0123456789" d))
+                               (upper (char-at "ABCDEFGHIJKLMNOP" (- d 10)))
+                               (else (char-at "abcdefghijklmnop" (- d 10))))))
+                      (begin (set! out (str c out)) (set! v (floor (/ v base))) (ib-loop)))))))
+            (ib-loop)
+            (str sign out)))))))
+
 (define
   lua-string-format
   (fn (&rest args)
@@ -1158,24 +1191,90 @@
                 (let ((c (char-at fmt i)))
                   (cond
                     ((and (= c "%") (< (+ i 1) (len fmt)))
-                      (let ((spec (char-at fmt (+ i 1))))
-                        (cond
-                          ((= spec "%")
-                            (begin (set! out (str out "%")) (set! i (+ i 2)) (loop)))
-                          ((= spec "s")
+                      (let ((j (+ i 1)) (left-align false) (zero-pad false) (width 0) (prec -1))
+                        (begin
+                          (when (and (< j (len fmt)) (= (char-at fmt j) "-"))
+                            (begin (set! left-align true) (set! j (+ j 1))))
+                          (when (and (< j (len fmt)) (= (char-at fmt j) "0"))
+                            (begin (set! zero-pad true) (set! j (+ j 1))))
+                          (define
+                            wd-loop
+                            (fn ()
+                              (when (and (< j (len fmt)) (>= (char-at fmt j) "0") (<= (char-at fmt j) "9"))
+                                (begin
+                                  (set! width (+ (* width 10) (- (char-code (char-at fmt j)) (char-code "0"))))
+                                  (set! j (+ j 1))
+                                  (wd-loop)))))
+                          (wd-loop)
+                          (when (and (< j (len fmt)) (= (char-at fmt j) "."))
                             (begin
-                              (set! out (str out (lua-concat-coerce (nth vals vi))))
-                              (set! vi (+ vi 1)) (set! i (+ i 2)) (loop)))
-                          ((= spec "d")
-                            (begin
-                              (set! out (str out (lua-format-int (nth vals vi))))
-                              (set! vi (+ vi 1)) (set! i (+ i 2)) (loop)))
-                          ((= spec "f")
-                            (begin
-                              (set! out (str out (str (nth vals vi))))
-                              (set! vi (+ vi 1)) (set! i (+ i 2)) (loop)))
-                          (else
-                            (begin (set! out (str out c)) (set! i (+ i 1)) (loop))))))
+                              (set! prec 0)
+                              (set! j (+ j 1))
+                              (define
+                                pr-loop
+                                (fn ()
+                                  (when (and (< j (len fmt)) (>= (char-at fmt j) "0") (<= (char-at fmt j) "9"))
+                                    (begin
+                                      (set! prec (+ (* prec 10) (- (char-code (char-at fmt j)) (char-code "0"))))
+                                      (set! j (+ j 1))
+                                      (pr-loop)))))
+                              (pr-loop)))
+                          (when (< j (len fmt))
+                            (let ((spec (char-at fmt j)))
+                              (cond
+                                ((= spec "%")
+                                  (begin (set! out (str out "%")) (set! i (+ j 1))))
+                                ((= spec "s")
+                                  (let ((v (lua-concat-coerce (nth vals vi))))
+                                    (let ((vt (if (and (>= prec 0) (< prec (len v))) (substring v 0 prec) v)))
+                                      (begin
+                                        (set! out (str out (lua-fmt-pad vt width left-align false)))
+                                        (set! vi (+ vi 1))
+                                        (set! i (+ j 1))))))
+                                ((= spec "d")
+                                  (let ((v (lua-fmt-int-base (lua-to-number (nth vals vi)) 10 false)))
+                                    (begin
+                                      (set! out (str out (lua-fmt-pad v width left-align zero-pad)))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                ((= spec "x")
+                                  (let ((v (lua-fmt-int-base (lua-to-number (nth vals vi)) 16 false)))
+                                    (begin
+                                      (set! out (str out (lua-fmt-pad v width left-align zero-pad)))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                ((= spec "X")
+                                  (let ((v (lua-fmt-int-base (lua-to-number (nth vals vi)) 16 true)))
+                                    (begin
+                                      (set! out (str out (lua-fmt-pad v width left-align zero-pad)))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                ((= spec "o")
+                                  (let ((v (lua-fmt-int-base (lua-to-number (nth vals vi)) 8 false)))
+                                    (begin
+                                      (set! out (str out (lua-fmt-pad v width left-align zero-pad)))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                ((= spec "f")
+                                  (let ((v (str (lua-to-number (nth vals vi)))))
+                                    (begin
+                                      (set! out (str out (lua-fmt-pad v width left-align zero-pad)))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                ((= spec "c")
+                                  (let ((v (lua-char-one (lua-to-number (nth vals vi)))))
+                                    (begin
+                                      (set! out (str out v))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                ((= spec "q")
+                                  (let ((v (str "\"" (lua-concat-coerce (nth vals vi)) "\"")))
+                                    (begin
+                                      (set! out (str out v))
+                                      (set! vi (+ vi 1))
+                                      (set! i (+ j 1)))))
+                                (else (begin (set! out (str out c)) (set! i (+ i 1)))))))
+                          (loop))))
                     (else
                       (begin (set! out (str out c)) (set! i (+ i 1)) (loop))))))))
           (loop)
diff --git a/lib/lua/scoreboard.json b/lib/lua/scoreboard.json
index ece8ffe3..ef127e69 100644
--- a/lib/lua/scoreboard.json
+++ b/lib/lua/scoreboard.json
@@ -1,8 +1,8 @@
 {
   "totals": {
     "pass": 1,
-    "fail": 11,
-    "timeout": 4,
+    "fail": 7,
+    "timeout": 8,
     "skip": 8,
     "total": 24,
     "runnable": 16,
@@ -10,11 +10,11 @@
   },
   "top_failure_modes": [
     [
-      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      7
+      "timeout",
+      8
     ],
     [
-      "timeout",
+      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
       4
     ],
     [
@@ -24,10 +24,6 @@
     [
       "undefined symbol: fat\\",
       1
-    ],
-    [
-      "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
-      1
     ]
   ],
   "results": [
@@ -47,7 +43,7 @@
       "name": "attrib.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8008
+      "ms": 8000
     },
     {
       "name": "big.lua",
@@ -59,7 +55,7 @@
       "name": "calls.lua",
       "status": "fail",
       "reason": "undefined symbol: fat\\",
-      "ms": 6184
+      "ms": 6732
     },
     {
       "name": "checktable.lua",
@@ -71,7 +67,7 @@
       "name": "closure.lua",
       "status": "timeout",
       "reason": "per-test timeout",
-      "ms": 8001
+      "ms": 8005
     },
     {
       "name": "code.lua",
@@ -81,9 +77,9 @@
     },
     {
       "name": "constructs.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to compare incompat",
-      "ms": 7870
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8007
     },
     {
       "name": "db.lua",
@@ -95,13 +91,13 @@
       "name": "errors.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 3808
+      "ms": 4579
     },
     {
       "name": "events.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 7990
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8007
     },
     {
       "name": "files.lua",
@@ -119,13 +115,13 @@
       "name": "literals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2085
+      "ms": 2829
     },
     {
       "name": "locals.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 1811
+      "ms": 2598
     },
     {
       "name": "main.lua",
@@ -137,19 +133,19 @@
       "name": "math.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"lua: attempt to call non-functio",
-      "ms": 4436
+      "ms": 6606
     },
     {
       "name": "nextvar.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 7759
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8008
     },
     {
       "name": "pm.lua",
-      "status": "fail",
-      "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 6473
+      "status": "timeout",
+      "reason": "per-test timeout",
+      "ms": 8009
     },
     {
       "name": "sort.lua",
@@ -161,19 +157,19 @@
       "name": "strings.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 4366
+      "ms": 6228
     },
     {
       "name": "vararg.lua",
       "status": "fail",
       "reason": "other: Unhandled exception: \\\"Unhandled exception: \\\\\\\"assertion failed!\\\\\\\"\\",
-      "ms": 2422
+      "ms": 3087
     },
     {
       "name": "verybig.lua",
       "status": "pass",
       "reason": "",
-      "ms": 1077
+      "ms": 1058
     }
   ]
 }
\ No newline at end of file
diff --git a/lib/lua/scoreboard.md b/lib/lua/scoreboard.md
index 060e4435..50da0d66 100644
--- a/lib/lua/scoreboard.md
+++ b/lib/lua/scoreboard.md
@@ -1,15 +1,14 @@
 # Lua-on-SX conformance scoreboard
 
 **Pass rate:** 1/16 runnable (6.2%)
-fail=11 timeout=4 skip=8 total=24
+fail=7 timeout=8 skip=8 total=24
 
 ## Top failure modes
 
-- **7x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
-- **4x** timeout
+- **8x** timeout
+- **4x** other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\
 - **2x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio
 - **1x** undefined symbol: fat\
-- **1x** other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat
 
 ## Per-test results
 
@@ -17,25 +16,25 @@ fail=11 timeout=4 skip=8 total=24
 |---|---|---|---:|
 | all.lua | skip | driver uses dofile to chain other tests | 0 |
 | api.lua | skip | requires testC (C debug library) | 0 |
-| attrib.lua | timeout | per-test timeout | 8008 |
+| attrib.lua | timeout | per-test timeout | 8000 |
 | big.lua | timeout | per-test timeout | 8007 |
-| calls.lua | fail | undefined symbol: fat\ | 6184 |
+| calls.lua | fail | undefined symbol: fat\ | 6732 |
 | checktable.lua | skip | internal debug helpers | 0 |
-| closure.lua | timeout | per-test timeout | 8001 |
+| closure.lua | timeout | per-test timeout | 8005 |
 | code.lua | skip | bytecode inspection via debug library | 0 |
-| constructs.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to compare incompat | 7870 |
+| constructs.lua | timeout | per-test timeout | 8007 |
 | db.lua | skip | debug library | 0 |
-| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3808 |
-| events.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7990 |
+| errors.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4579 |
+| events.lua | timeout | per-test timeout | 8007 |
 | files.lua | skip | io library | 0 |
 | gc.lua | skip | collectgarbage / finalisers | 0 |
-| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2085 |
-| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 1811 |
+| literals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2829 |
+| locals.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 2598 |
 | main.lua | skip | standalone interpreter driver | 0 |
-| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 4436 |
-| nextvar.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 7759 |
-| pm.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6473 |
+| math.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"lua: attempt to call non-functio | 6606 |
+| nextvar.lua | timeout | per-test timeout | 8008 |
+| pm.lua | timeout | per-test timeout | 8009 |
 | sort.lua | timeout | per-test timeout | 8007 |
-| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 4366 |
-| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 2422 |
-| verybig.lua | pass | - | 1077 |
+| strings.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 6228 |
+| vararg.lua | fail | other: Unhandled exception: \"Unhandled exception: \\\"assertion failed!\\\"\ | 3087 |
+| verybig.lua | pass | - | 1058 |
diff --git a/lib/lua/test.sh b/lib/lua/test.sh
index bc846a73..ef794195 100755
--- a/lib/lua/test.sh
+++ b/lib/lua/test.sh
@@ -994,6 +994,20 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 1912)
 (eval "(lua-eval-ast \"return string.match(\\\"abc\\\", \\\"[^a]+\\\")\")")
 
+;; ── string.format width/precision/hex/octal/char ─────────────
+(epoch 1920)
+(eval "(lua-eval-ast \"return string.format('%5d', 42)\")")
+(epoch 1921)
+(eval "(lua-eval-ast \"return string.format('%05d', 42)\")")
+(epoch 1922)
+(eval "(lua-eval-ast \"return string.format('%x', 255)\")")
+(epoch 1923)
+(eval "(lua-eval-ast \"return string.format('%X', 255)\")")
+(epoch 1924)
+(eval "(lua-eval-ast \"return string.format('%c', 65)\")")
+(epoch 1925)
+(eval "(lua-eval-ast \"return string.format('%.3s', 'hello')\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1508,6 +1522,14 @@ check 1910 "[a-z]+ on hello123"             '"hello"'
 check 1911 "[0-9]+ on hello123"             '"123"'
 check 1912 "[^a]+ on abc"                   '"bc"'
 
+# ── string.format width/precision/hex/octal/char ────────────
+check 1920 "%5d width"                      '"   42"'
+check 1921 "%05d zero-pad"                  '"00042"'
+check 1922 "%x hex"                         '"ff"'
+check 1923 "%X HEX"                         '"FF"'
+check 1924 "%c char"                        '"A"'
+check 1925 "%.3s precision"                 '"hel"'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL Lua-on-SX tests passed"
diff --git a/plans/lua-on-sx.md b/plans/lua-on-sx.md
index 4d933d56..719fa5c8 100644
--- a/plans/lua-on-sx.md
+++ b/plans/lua-on-sx.md
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-25: lua: scoreboard iteration — extended `string.format`. New `%x`/`%X`/`%o` (hex/octal), `%c` (codepoint→char via `lua-char-one`), `%q` (basic quote), width N (`%5d`), zero-pad (`%05d`), left-align (`%-5d`), `%.Ns` precision. Helpers `lua-fmt-pad` and `lua-fmt-int-base`. 393/393 green (+6 format tests).
 - 2026-04-25: lua: scoreboard iteration — `lua-eval-ast` now SKIPS the top-level guard when the parsed chunk has no top-level `return` (recursive AST walk via `lua-has-top-return?` that descends through control-flow but stops at function-body boundaries). Without the guard, top-level user defines leak to the SX top env, and `loadstring`-captured closures can find them. Verified: `function fat(x)...loadstring("return fat(...)")...end; x=fat(5)` works (was undefined). Most PUC-Rio tests still have top-level returns elsewhere, so they still need the guard. Scoreboard unchanged at 1/16 but unblocks future work.
 - 2026-04-25: lua: scoreboard iteration — math fns now error on bad/missing args (was silently returning 0). New `lua-math-num "name" x` validator wraps `abs`/`ceil`/`floor`/`sqrt`/`exp`/`sin`/`cos`/`tan`/`asin`/`acos`/`atan`/`atan2`/`pow`. errors.lua moves past assert #4 (`pcall(math.sin)` now returns false+err as expected).
 - 2026-04-24: lua: scoreboard iteration — **pattern character sets** `[...]` and `[^...]`. New `lua-pat-set-end`/`lua-pat-set-match` helpers handle ranges (`[a-z]`), classes inside sets (`[%d%a]`), negation (`[^abc]`), and `[]...]`/`[^]...]` (literal `]` as first char). Asserts 6→4, but timeouts 3→7 — many tests now reach loop-heavy code. 387/387 green (+3 charset tests).